The invention relates to a method for recirculating a partial exhaust gas flow to an internal combustion engine of a motor vehicle. The invention also relates to a device for carrying out the method.
Methods for recirculating partial exhaust gas flows to an internal combustion engine are known. DE-Patent 196 80 305 C2 describes an exhaust gas recirculation system for an internal combustion engine. In this system, some of the exhaust gases produced by the engine are recirculated from an exhaust line of the engine into an intake line of the engine, the exhaust gas recirculation system having a recirculation line downstream of the exhaust line of the engine. This recirculation line splits into a bypass line and a radiator line having an integrated radiator. The bypass line and the radiator line each have a valve at their end, downstream of which the bypass line and the radiator line are once again combined into a single line. The partial exhaust gas flow then flows back into the engine via this line. A disadvantage of this method is however that the two valves become clogged relatively quickly by particulates and condensate products in the exhaust gas, which affects both the actual operation and the actuation of the two valves which are completely opened or completely closed alternately to one another. The valves are actuated by an electronic control unit such that the partial exhaust gas flow flows via the bypass line in operating modes at low engine temperature or low engine load, and via the radiator line in other engine operating modes. The clogging of the valves has an adverse effect on the actuation by the electronic control unit so that varying exhaust gas conditions can only be reacted to with a time lag. It is therefore the object of the invention to provide a method for recirculating a partial exhaust gas flow to an internal combustion engine of a motor vehicle in which clogging of shut-off valves is largely prevented. It is also the object of the invention to produce a device for carrying out the method.